The use of laser energy to perform surgical procedures on living tissue is becoming more common. Typically, the laser energy is transmitted through an optical fiber to the surgical site. The optical fiber is usually included in a catheter or similar assembly which is inserted into the body through a small incision or a body orifice. In some applications, optical fiber assemblies are used in conjunction with endoscopes to perform surgical procedures on the gallbladder and urinary tract. In other applications, a hand-held laser system may be used to cut or cauterize living tissue.
A typical laser catheter includes a glass or silica fiber and a tubular shaft which axially surrounds the fiber. One end of the fiber and shaft are connected to a coupling device which optically couples the fiber to a source of laser radiation. Bending or torquing the optical fiber along a small bend radius adversely affects the transmission properties of the fiber and ultimately the efficiency of the whole laser system. Some laser catheters include strain relief devices disposed about the proximal end of the catheter shaft to limit the radius to which the proximal end of the fiber is bent relative to the axis of the laser source. Most strain relief devices, however, do not provide any means for maintaining the optical fiber in axial alignment with the laser source at the point where the fiber emerges from the coupling mechanism. Accordingly, it is an object of the present invention to improve the transmission property of an optional fiber assembly by providing an improved strain relief device which maintains the axial alignment of the proximal end of the fiber with laser source.
A problem associated with the transmission of laser energy through an optical fiber relates to cooling of the fiber. The propagation of laser energy through the fiber results in rapid heating of the fiber core and cladding. In some laser catheters, fluid is introduced into the space intermediate the optical fiber and the wall of the catheter shaft to help dissipate heat from the fiber. Such catheters require special coupling connectors, to introduce the fluid into the interior of the catheter shaft. Most such coupling connectors are fixed to the catheter shaft and require bending of the shaft, and optical fiber, to properly couple the connector to a source of cooling medium. As explained above, bending or torquing of the fiber axis adversely affects its transmissive properties.
Accordingly, it is an object of the present invention to provide a connector for supplying a cooling medium to a catheter shaft which may be rotatably mounted within the shaft to facilitate operative coupling to a source of cooling medium which may be located at any arcuate position relative to the axis of the catheter and optical fiber.
In hand-held or "hot knife" laser delivery systems, the distal end of the optical fiber extends through a handle mechanism and a stainless steel stem. During the assembly of such systems the optical fiber is threaded through the handle mechanism into the stainless steel stem and distally therebeyond. In prior art handle mechanisms, upon insertion of the stainless steel stem into the handle portion, a shoulder or abrupt decrease in the diameter of the handle bore is often formed at the junction of the stem and the handle. When the optical fiber is subsequently threaded through the handle and into the stem, the distal tip of the fiber often grazes or collides with the shoulder formed at the junction of the handle and stem. Such contact often chips or damages the extreme distal tip of the optical fiber which has a precision sculpted shape, as required by the specific surgical procedure. Any damage to the distal tip of the fiber also adversely affects the transmissive properties of the fiber and, ultimately, the utility of the whole laser system. Also, the manner in which the stem is inserted into the handle directly effects the integrity of the handle/stem joint and the tendency for the stem to rotate relative to the axis of the handle.
Accordingly, it is an object of the present invention is to provide a handle apparatus for a hand-held laser system in which the optical fiber may be threaded through the handle without the risk of damaging the distal tip of the optical fiber.
A further object of the present invention to provide a handle apparatus for use with a hand held laser delivery system in which the internal bore of the handle and stem, particularly at the handle/stem juncture, tapers smoothly to eliminate any obstructions or projections which may damage the tip of the optical fiber upon insertion.
Another object of the present invention is to provide handle apparatus for a hand held laser system in which a strong joint is formed between the stem and the handle, and which further reduces the tendency for the stem to rotate within the handle.
Yet another object of the present invention is to provide a handle apparatus for a hand-held laser system in which the handle is molded about the stem portion of the handle mechanism.
Another object of the present invention is to provide a laser delivery system with improved transmissive properties by maintaining the axial alignment of the optical fiber with a source of laser radiation at its point of coupling and for an increased distance therebeyond.
A further object of the present invention is to provide a laser delivery system having an improved strain relief mechanism which limits the bend radius over a substantial portion of the fiber proximal end.
Yet another object of the present invention is to provide a laser delivery system having a strain relief mechanism which supports the proximal end of the fiber and maintains axial alignment between the fiber and the laser source at its proximal end.
Still a further object of the present invention is to provide a laser delivery system in which the optical fiber is fluid cooled.
Yet another object of the present invention is to provide a laser delivery system in which a cooling medium is introduced into the laser catheter shaft by a connector which is rotatably mounted to the catheter.
A further object of the present invention is to provide a connector for introducing a cooling medium into a catheter shaft which is rotatably mounted to the catheter shaft allowing the source of cooling medium to be disposed at any arcuate position about the axis of the optical fiber.